Collect paint sample cards of various hues, making sure you get two of the same color hue. For example, you might want to pick out three hues of pink, but get two of each of those pinks.
Set out all of the cards in your center or use these as a small group activity. Have children spread out the cards on a table and match the pairs of cards that are the same color hue.
If children are a little overwhelmed, you might want to only put out a few at a time. Maybe place only three green cards with their pairs, and have children match those first. For more advanced children, you could add more hues to each color.
Extend the Activity
To extend the activity, have children look for objects around the room that match the color cards. Perhaps a pink crayon will match one of the pink cards, or a wood block might match a light tan card.
Take a set of cards outside and have children match natural objects to the cards. They could find leaves that match the green cards or flowers that match some of the cards. Maybe they could hold up blue or gray cards to the sky and see which hues match the sky that day.
Just a little terminology: A color hue means a variation of a color, where white or black or another color has been added to it. A tint of a color is a lighter variation, where white has been added to it (in other words, pale hues). A shade of a color is a darker variation, where black has been added to it (darker hues).